Yeah, I can actually understand their thinking >"Well this is the first time we've seen a shirtless Joker in live-action, we should do something more visually memorable than just a plain white torso.">"How bout tattoos? Jim Lee drew him with these Yakuza dragon tats in the comics.">"Why the hell would the Joker have Japanese style tats? Nah, make them clown-themed."
Put his top back on, and he looks the most like the comic book Joker in terms of makeup and build - but that damned DAMAGED tat is still there, still stupid. It's like if Batman had a second, smaller Bat-logo on the forehead of his cowl.